With Windows 10 coming out soon, there are still a lot of Windows Phone 8 apps around. Those apps didn’t get an update to Windows Phone 8.1. And of course, that’s not a big problem, because Windows Phone 8 apps still run on Windows Phone 8.1.

With Windows 10 it may be different.

With the release of Windows Phone 8.1, Microsoft pushed the Silverlight apps (Windows Phone 8 apps) to the background, and we can see this going further with Windows 10. At the moment it’s not possible to develop Universal Apps with Silverlight, and probably it’ll not be supported in Windows 10 either. Since the whole Windows 10 experience is based around an equal experience on every device, every app should be able to run on every device. And that’s just not possible with the classic Windows Phone 8 apps.

With Windows 10 the user interface will change a lot as well, so it wouldn’t feel like a nice and native experience to run a Windows Phone 8 app on Windows 10 mobile. Aside from that it will be much easier to upgrade your apps from Windows 8.1 to Windows 10, when it still are Windows Phone 8 this will be harder.

Another reason why you might want to update your app to Windows Phone 8.1 is that most of the Windows Phone 8 devices can be upgraded to 8.1 for free. Along with the fact that you almost can’t get Windows Phone 8 devices anymore, so the Windows Phone 8 user base is only shrinking. The current user base of Windows Phone 8.1 (1.38%) is almost three times the size of the Windows Phone 8 user base (0.48%), according to Netmarketshare. As you can see in the following charts.

Windows Phone 8 market share: [netmarketshare.com]

Windows Phone 8.1 market share: [netmarketshare.com]

It’s even possible that Microsoft will stop letting Windows Phone 8 apps run on Windows 10. So why wouldn’t you want to keep up and get your apps ready for the future?